Rubber refers to those with reversible deformationHigh elasticityPolymer materials, elastic at room temperatureExternal force actionIt can produce large deformation and recover after removing external force.Rubber is completelyamorphous Polymer, itsGlass transition temperature(T g) is low, and the molecular weight is often very large, more than hundreds of thousands.
The word "rubber" comes from the Indian language cau uchu, which means "tearful tree".Natural rubberIt is composed of three leavesRubber treeOutflow during tappinglatexIt is prepared after solidification and drying.In 1770, British chemist J. Priestley found that rubber could be used to erase pencil writing. At that time, the material for this purpose was calledrubber, this word has always been used.The molecular chain of rubber can be crosslinked, and the crosslinked rubber is subject toExternal force actionIn case of deformation, it has the ability of rapid recovery and good physicsmechanical property andchemical stability。Rubber is the basic raw material of the rubber industry, which is widely used to manufacture tires, rubber hoses, tapes, cables and other kinds ofRubber products。Three leaf rubber trees provide the most commercial rubber.When it is injured (such as the bark of the stem is cut off), it will secrete a large amount of rubber emulsionSap。
In addition,Fig treeAnd someEuphorbiaceaeOur plants can also provide rubber.Germany inthe Second World WarWhen the rubber supply was cut off, an attempt was made to obtain rubber from these plants, but later the production of artificial rubber was changed.
initialRubber treeGrowing onSouth America, but after manual transplantation,Southeast AsiaThere are also a lot of rubber trees.in fact,AsiaIt has become the most important source of rubber.
Natural rubber is made fromlatexManufactured, some of the non rubber ingredients contained in the latex remain in the solid natural rubber.General natural rubber containsRubber hydrocarbon92% - 95%, while non rubber hydrocarbon accounts for 5% - 8%.Due to different preparation methods, different origins and even different rubber picking seasons, the proportions of these ingredients may vary, but they are basically within the range.
proteinIt can promote the vulcanization of rubber and delay aging.On the other hand, protein has strongWater absorption, can cause rubberHygroscopicMildewInsulationThe protein has the disadvantage of increasing heat generation.
The moisture content in the dry rubber is not more than 1%, which can volatilize during processing. However, if the moisture content is too high, it will not only make the raw rubber easy to mold during storage, but also affect the rubber processing, such asMixingThe mixture is easy to agglomerate;Bubbles are easily generated during rolling and extrusion,Vulcanization processBubbles or spongy, etc.
structure
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Foam rubber sponge
linear structure : NotVulcanized rubberThe universal structure of.Because of its large molecular weight,Macromolecular chainIt is in the shape of random coil curve.When the external force acts, remove the external forceconcurrence When changes occur, the molecular chain rebounds, resulting in a strong tendency to recover, which is the origin of rubber's high elasticity.
Branched chainStructure: Aggregation of branch chains of rubber macromolecule chains to form gels.Gels are detrimental to the properties and processing of rubber.When mixing rubber, various compounding agents often cannot enter the gel area, forming a local blank, which can not be reinforced and cross-linked, becoming the weak part of the product.
Sources and application characteristics of general-purpose rubber
rubber
General purpose rubber has good comprehensive properties and is widely used.It mainly includes: ① natural rubber, which is made from the latex of clover rubber treechemical compositionIs cis-Polyisoprene。Good elasticity, high strength and good comprehensive performance. ②Isoprene rubberIts full name is cis-1,4-polyisoprene rubber. The highly cis synthetic rubber made from isoprene is also called because its structure and properties are similar to those of natural rubberSynthetic natural rubber。③Styrene butadiene rubber (SBR for short) is prepared by copolymerization of butadiene and styrene.PressProduction methodDivided intoemulsion polymerization SBR and solution polymerized SBR.Its comprehensive performance and chemical stability are good. ④Cis-1,4-polybutadiene rubber (BR for short) is polymerized from butadiene.Compared with other general-purpose rubbers, cured cis-1,4-polybutadiene rubber has excellent cold resistance, abrasion resistance and elasticityfeverLess, good aging resistance, easy to mix with natural rubber, neopreneNitrile rubberAnd so on. ⑤Chloroprene rubber, CR for short, is polymerized from chloroprene.It has good comprehensive performance, oil resistance, flame resistance, oxidation resistance and ozone resistance.However, its density is high, it is easy to crystallize and harden at room temperature, its storage property is poor, and its cold resistance is poor.
Source and application characteristics of special rubber
Special rubber refers to rubber with some special properties.It mainly includes: ① nitrile rubber, NBR for short, is prepared by copolymerization of butadiene and acrylonitrile.It has good oil resistance and aging resistance, and can be used for a long time in 120 ℃ air or 150 ℃ oil.In addition, it has water resistanceAir tightnessAnd excellent bonding performance. ②silicon rubberThe main chain is composed of alternate silicon oxygen atoms with organic groups on the silicon atoms.High and low temperature resistance, ozone resistance, good electrical insulation. ③Viton,molecular structureFluorinatedsynthetic rubber。UsuallycopolymerIs represented by the number of fluorine atoms of the fluorine containing unit, such asViton 23, YesVinylidene fluoridewithChlorotrifluoroethyleneCopolymer of.Fluorine rubber is resistant to high temperature, oil and chemical corrosion. ④Polysulfide rubber, composed of twoHaloalkaneAndalkali metaloralkaline-earth metalOfPolysulfideIt is condensed.Excellent oil resistance andSolvent resistance, but with low strength, aging resistanceProcessabilityBad, smelly, mostly used with nitrile rubber.In additionPolyurethane rubber、Chlorohydrin rubber, acrylate rubber, etc.
Influence of rubber structure
Rubber reinforcementThe performance impact is mainly aimed attensile strength andtear strength Uppergeneral ruleYes: when the particle size is the same, the high structure carbon black has a great reinforcement effect on the amorphous rubber, and generally has a high tensile strength and tear strength.Rubber structure is also the most important factor affecting the electrical conductivity. The chain branch structure is easy to form an interlaced conductive path in rubber, which will improve the electrical conductivity.
Rubber classification
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rubber
It can be divided into block raw rubber, latexLiquid rubberandPowdered rubber。Latex is colloidal water of rubberDispersion；Liquid rubber is rubberOligomerBefore vulcanization, it is generally viscous liquid;Powdered rubber is to process latex into powder for easy batching and processing.Developed in the 1960sThermoplastic rubber, without chemical vulcanizationThermoplasticThe processing method for forming.According to the use, rubber can be divided into general type and special type.yesinsulatorIt is not easy to conduct electricity, but it may become a conductor if it is immersed in water or at different temperatures.Conduction refers to the easy conduction of electrons of molecules or ions inside a substance.According to the source and method of raw materials: rubber can be divided into natural rubber andsynthetic rubberTwo categories.Natural rubberConsumptionIt accounts for 1/3, and the consumption of synthetic rubber accounts for 2/3.
According to the appearance of rubber, rubber can be divided into four categories: solid rubber (also known as dry rubber), emulsion rubber (referred to as latex), liquid rubber and powder rubber.
According to the properties and uses of rubber: except for natural rubber, synthetic rubber can be divided intoGeneral purpose synthetic rubber, semi universal synthetic rubber, special synthetic rubber andSpecial synthetic rubber。
According to the physical form of rubber, rubber can be divided into hard rubber andSoft gum, raw rubber andRubber mixtureEtc.
Natural rubber mainly comes from cloverRubber treeWhen the skin of the rubber tree is cut, milky juice will flow out, called latex. The latex will be condensed, washed, shaped and dried to obtain natural rubber.Synthetic rubber is made by artificial synthesis. Different kinds of rubber can be synthesized by using different raw materials (monomers).1900-1910 Chemist CD. Harris determined that the structure of natural rubber isisopreneOfhigh polymerThis opens up a way for synthetic rubber.1910RussiaChemist SVLebedev(Lebedev, 1874-1934)sodiumbyInitiatorPolymerize 1,3-butadiene intoBuna rubberAfter that, many new synthetic rubber varieties have emerged, such asCis-1,4-polybutadiene rubber、Neoprene、butadiene styrene rubberwait.The output of synthetic rubber has greatly exceeded that of natural rubber, of which styrene butadiene rubber is the largest.
General purpose rubber
It refers to the type of rubber that partially or completely replaces natural rubber, such as styrene butadiene rubber, cis-1,4-polybutadiene rubberIsoprene rubberMainly used in tire manufacturing and general industryRubber products。Universal rubberrequirementLarge, is the main variety of synthetic rubber.
Silicone rubber consists of siliconOxygen atomForm the main chain,Side chainIs a carbon containing group, and the maximum amount of side chain isethyleneSilicone rubber.It is both heat-resistant and cold resistant. The service temperature is between 100-300 ℃. It has excellentWeather resistanceAnd ozone resistance to use goodInsulation。The disadvantages are low strength, poor tear resistance and wear resistance.Silicone rubber is mainly used foraviation industry, electrical industryfood industryAnd medical industry.
Cis-1,4-polybutadiene rubber
Rubber tyre
Is butadiene viasolution polymerization The prepared cis-1,4-polybutadiene rubber has particularly excellent cold resistance, abrasion resistance and elasticity, and also has good aging resistance.Most of cis-1,4-polybutadiene rubber is used to produce tires, and a small part is used to manufacture cold resistant productsCushioning materialAnd tapeRubber overshoesEtc.The disadvantage of cis-1,4-polybutadiene rubber is its resistance toTear resistance Poor, poor wet skid resistance.
Isoprene rubber
Isoprene rubber isPolyisoprene rubberAbbreviation of, usingSolution polymerizationProduction.Like natural rubber, isoprene rubber has good elasticity and abrasion resistanceHeat resistanceAnd betterchemical stability。The strength of raw isoprene rubber (before processing) is significantly lower than that of natural rubber, but the qualityHomogeneityProcessing performance is superior to natural rubber.Isoprene rubber can replace natural rubber to manufacture truck tires andOff road tiresIt can also be used to produce various rubber products.
Ethylene propylene rubber with ethylene andpropyleneIt is synthesized from main raw materials and is resistant to aging and electricityInsulation performanceAnd ozone resistance.EPDM can be filled with oilcarbon blackThe price of products is low, and the chemical stability of ethylene propylene rubber is good, and the wear resistance, elasticity and oil resistance are similar to those of styrene butadiene rubber.Ethylene propylene rubber has a wide range of applications. It can be used as tire sidewall, rubber strip, inner tube and auto parts, as well as wire, cable sheath and high-voltageUltrahigh pressureInsulating material。It can also manufacture light colored products such as rubber shoes and sanitary products.
Neoprene
It is based onChloropreneAs the main raw materialHomopolymerizationOr a small amount of other monomers.asTensile strengthHigh heat resistance, light resistance, aging resistance, oil resistance are superior to natural rubber, styrene butadiene rubber, cis-1,4-polybutadiene rubber.With strongFlame resistanceAnd excellent flame retardancy, with high chemical stability,Water resistanceGood.The disadvantages of neoprene rubber are electrical insulation performance, poor cold resistance and instability of raw rubber during storage.Neoprene is widely used, such as for making transportation belts andDrive belt, covering materials of wires and cables, manufacturing oil resistant rubber pipes, gaskets andChemical corrosionEquipment lining.
The rubber industry isnational economyThe importance ofbasic industry one of.It not only provides people with light industrial rubber products for daily use and medical use that are indispensable in daily life, but also provides mining, transportation, construction, machinery, electronics, etcheavy industryandEmerging industriesProvide various rubberProduction equipmentOr rubber parts.It can be seen that the rubber industry has a wide range of products, and the backward industry is very broad.
The rubber industry has developed a lotSegmented industriesWith steady growth, the new rubber segment industry has developed rapidly, but at the same time, the rubber industry also has problems such as environment, resources, disasters and innovation.
In 2004, the total planting area of natural rubber nationwide was 696200 hectares, the cutting area was 451900 hectares, and the dry rubber output was 573300 tons.Including agricultural reclamation rubberplanting area411000 hectares and 285200 hectares are privately owned, accounting for 59.03% and 40.97% of the total rubber area in China respectively.
In 2005,HainanEncountered a rare drought in 50 years and a once-in-a-centurytyphoon disaster The production of natural rubber suffered a heavy blow.To excavate domestic natural rubber planting and processingdevelopment potentialChina's rubber industry has made unremitting efforts to increase self-sufficiency and conscientiously implement national security, energy conservation, environmental protection andcleaner production And achieved significant results.In particular, the rubber additives industry actively adjusted the product structure, and green environment-friendly additives increased significantly. The proportion of production of excellent varieties of antioxidant has reached 80%, and the proportion of promoters has reached 50%. NOBS is toxic, harmful, and highly carcinogenicoutputobtainEffective control；Waste rubber comprehensiveUtilizationOver 65%,Reclaimed rubberandColloidal powderThe field of post-processing and utilization has expanded.
In 2006,China Rubber Industry AssociationThe third session of the sixth session of the Council discussed, adopted and issued the Opinions on the "Eleventh Five Year" Scientific Development Plan of China's Rubber Industry and the Opinions on the "Eleventh Five Year" Brand Strategy Plan of the Rubber Industry.This is the first time that it is formulated by the associationIndustry planning。The plan shows that the rubber industry should take the road of independent innovation during the 11th Five Year Plan period, and the whole industry should effectively turn to the track of scientific development, so that China will become a strong country in the world rubber industry.
China's rubber industry has broad prospects for development.By 2010, the total consumption of natural rubber in China will reach 2.3 million tons, and the product mix of the rubber industry will be greatly changed. New products, newer products, new materials, and new processes will be expanded,Production technologySignificant progress has been made.
The characteristics of the rubber industry determine that when a country's rubber industry matures, the prosperity of the industry and the overall economic operation will remain strongrelevance: The length of its development cycle and that of the countryeconomic cycle The length is the same and the trend is the same;But because the rubber industry belongs toBasic industry, itsPeriodic changeSlightly ahead of the economic cycle.In addition, the rubber industry is also located in the national economyProduction chainThe front end of theamplitudeIt should be smaller than the amplitude of the end industry of the industrial chain, and also smaller than the amplitude of the entire economy.Therefore, fromindustrial investment From the perspective of, mature rubber industry is close to income investment industry.Rubber in Chinaprocessing industryIn the period of vigorous development, the rubber industry in various regions has not only acceleratedChinese industryThis process has also led to a good situation of economic construction and development in various regions.China's rubber industry is relatively developed in Yunnan, Guangdong and ShandongJuxian County, Hebei, etc.
Rubber market
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The price of rubber raw materials fluctuates significantly, making it difficult to control the cost of enterprises
In 2011, the prices of raw materials such as rubber fluctuated dramatically. Natural rubber hit a record high of 43500 yuan/ton in the first quarter, while synthetic rubber made an upward march in the second and third quarters,IncreaseIt reached 10000 yuan/ton, and then fell sharply.Affected by the drastic fluctuation of rubber prices, major rubber products enterprises such as tires bear the brunt,Production and operation costsDifficult to control,Inventory riskenlarge,Profit spaceCompressed to 2% - 5%, the industry faces severe challenges.
The growth rate of the industry has fallen back rationally and entered the track of sound development
As the price of rubber raw materials fluctuates significantly, the domestic and foreign markets continue to be depressed,domestic market demandSlowing down, the output growth of China's main rubber products fell back, and the export fell back, but there was no big ups and downseconomical operation Overall stable.At the same time, the operation quality has been optimized:product mixProgress has been made in the adjustment, with the tire meridianization rate reaching 86.5%, up 2.5% year on year, and the structure of other products has also been greatly improved;The transformation of the growth mode of the rubber industry has achieved initial results, and the dependence of tires on external demand has decreased;implementlow-carbon economyThe effect is remarkable, the energy consumption of the industry is reduced, and a batch of energy-saving equipment appears,Green tireAnd green raw materials continue to emerge.These changes indicate that whenEconomic growth rateWhen it is moderately reduced, it will help to adjust the structure and promote various reforms.The economic operation of China's rubber industry has begun to enter the track of sound development.
From January to October in the first half of 2012, the main economic indicators of the domestic rubber industry continued to grow slightly, and the output growth of major rubber products continued to show a positive trendExport delivery valueThe growth rate dropped slightly compared with that of last month, and the industrial efficiency continued to maintain a positive trend.
data displayJanuary October 2012, ChinaRubber products industryCompleted industrial output valueYear on year growth6.47%, and the output of comprehensive casing increased by 2.59% year on year, of whichRadial tireThe output increased by 3.13% year on year, the output of all steel radial tire increased by 6.55% year on year, and the radial rate reached 87.23%, an increase of 0.46Percentage point。
At the same time, the whole industry realizessales revenueThe year-on-year growth rate was 6.26%, and the inventory increased by 7.06%,Ring ratioDecrease by 0.12%.The delivery value of exported tires increased by 11.29% year on year, and the export rate (value) was 34.23%, 1.48 percentage points higher than that of 2011.The delivery volume of exported tires increased by 5.87% year on year, and the export rate (volume) was 42.83%, 1.32 percentage points higher than that of 2011.
--Collect plant data in the field--
Chinese species name
rubber[1]
Latin name
Hevea brasiliensis
Family name
Euphorbiaceae
Acquisition time
August 6, 2009
Collection location
Donghe Town, Dongfang County, Hainan
Collector
Xing Fuwu, Dai Jianyue, Zheng Xilong
Type of sample collected
Fruit
Lifestyle
Medium arbor
ecological environment
Roadside
formula
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The basic formula shall be properly referred to for different rubber compounding ingredients, as follows
Natural rubber can be divided into standard rubber (also called granular rubber)Nicotine sheet、Concentrated glue, white crepe film, light color filmClear rubberAnd air dried film, the most commonly used are standard adhesive and cigarette adhesive.The standard adhesive is divided into four grades: Grade I (SCR5), Grade II (SCR10), Grade III (SCR20) and Grade IV (SCR50), and the cigarette adhesive is divided into five grades: No. 1-5 cigarette film (RSS1-RSS5).
Standard rubber: standard rubber is mainly divided into 5 # rubber, 10 # rubber and 20 # rubber.No. 5 glue is the first grade glue, which is the best glue and contains 0.05% impurities;No. 10 glue is the second grade glue, which contains 0.10% impurities;No. 20 adhesive is a third grade adhesive, which contains 0.20% impurities.Different types of rubber have different uses: No. 5 rubber is generally used to make inner tubes of tires;10 # rubber and 20 # rubber are generally used to make tire casing.
Cigarette sheet: ready to use combustionCoconut shellThe film obtained after the natural film with moisture removed is smoked by the smoke and heat generated.The purpose of smoking is to makeFilm dryingAnd inject anti oxidation and anti-corrosionCresolSubstance.Cigarette rubber sheet belongs to natural rubber in primary shape.
Concentrated glue: can be used as bonding material.
Crepe:
Super grade thin white crepe film
The delivered goods must be white, even, dry and solid rubber.
No discoloration, sour smell, dust, crumbs, gravel or others caused by any reason are allowedForeign matter, oil contamination or other signs of contamination, oxidation or overheating.
Grade I thin white crepe film
The delivered goods must be white, dry and solid rubber.A slight difference in shade is allowed.
Super grade thin light color crepe film
The delivered goods must be light colored, even, dry and solid rubber.
Grade I light crepe film
The delivered goods must be light colored, dry and solid rubber.A slight difference in shade is allowed.
Grade II light crepe film
The delivered goods must be dry and solid rubber.The color gloss is slightly deeper than that of the first grade thin light color crepe film.Slight color difference is allowed.
It is allowed to have spots andStreaksRubber.However, the number of such bags shall not exceed 10% of the inspected bags.
Except for those permitted above, there shall be no signs of discoloration, dust, chips, gravel or other foreign substances, oil stain or other stains, oxidation or overheating caused by any reason.
Three grade thin light color crepe film
The delivered goods must be light yellow, dry and solid rubber.Difference in color depth is allowed.
（Styrene Butadiene Copolymer）butadieneAndstyrene Copolymer, compared with natural rubber, has uniform quality, less foreign matter, better wear resistance andAging resistance, butmechanical strengthIt is weak and can be mixed with natural rubber.Advantages: low cost non oil resistant material, goodWater resistanceGood elasticity under hardness 70, poor elasticity under high hardnessCompressibility。Disadvantages: it is not recommended to use strong acid, ozone, oilOleateAnd fat and mosthydrocarboninWidely used in tire industry, shoe industry, cloth industry andConveyor beltIndustry, etc.
(Butyl Rubber) isisobutene It is polymerized with a small amount of isoprene. Because the movement of methyl steric barrier molecule is less than that of other polymers, the gas permeability is less and the resistance to heat, sunlight and ozone is greater,Electrical insulationGood sex;It has a strong resistance to polar solvent, and the general use temperature range is - 54-110 ℃.Advantages: Not applicable to most ordinary gasesPermeabilityIt has good resistance to sunlight and odor, and can be exposed to animal or vegetable oil or volatile chemicals.Disadvantages: not recommendedPetroleum solventKerosene and aromatic hydrogen are used at the same time.be used forAutomobile tireInner tube, leather bag, rubber paste paper, window frame rubber, steam hoseHeat resistant conveyor beltEtc.
Hydrogenate NickelButyronitrileThe rubber is the part removed from the nitrile rubber after hydrogenationDouble chain, temperature resistance after hydrogenationWeatherabilityMore than averageNitrile rubberImprove a lot,Oil resistanceSimilar to common nitrile rubber.The general operating temperature range is - 25-150 ℃.Advantages: better than nitrile rubberAbrasion resistanceIt has excellent corrosion resistance, tensile resistance, tear resistance and compression properties.
It has good resistance under atmospheric conditions such as ozone, and is generally used in detergents for washing clothes or dishes.Disadvantages: It is not recommended to be used in the hollow refrigeration industry of alcohols, esters or aromatic solutions. It is widely used for environmental protectionRefrigerant、R134aSeals in the systemautomobile engineSystem seals.
EPDM
Ethylene propylene rubber (EPDM) is composed ofethyleneandpropyleneCopolymerizationSoHeat resistance, aging resistance, ozone resistanceStabilityBoth are excellent, but cannotsulfurSulfonation.To solve this problem, a small amount of the third component with double chains is introduced into the EP main chain, which can be made into EPDM by adding sulfur. The general use temperature is - 50-150 ℃.yesPolar solventSuch as alcohol, ketone, etc. Excellent resistance Advantages: good weather resistance and ozone resistance, excellent water resistance and chemical resistance, alcohol andKetonesIt is resistant to high temperature steam and has good impermeability to gas.Disadvantages: Not recommended for food use or exposure to aromatic hydrogen.high temperatureWater vaporSeals of the environment Plumbing equipment seals or parts.Rubber parts in the brake (braking) system.radiatorSeal in (car water tank).
NBR
(Nickel Rubber)acrylonitrile Copolymerized with butadiene, with acrylonitrile content ranging from 18% to 50%. The higher the acrylonitrile content, the higher theHydrocarbonThe resistance of fuel oil is better, butLow temperature performanceThen it becomes worse, and the general use temperature range is minus 25-100 ℃.Acrylonitrile butadiene rubber isoil sealAnd one of the most common rubber advantages of O-ring: it has good characteristics of oil resistance, water resistance, solvent resistance and high pressure oil resistance.
It has good compressibility, abrasion resistance and elongation.
Disadvantages: not suitable for polar solvents, such as ketones, ozone, nitrohydrocarbons, MEK andchloroform. ?For productionFuel tank, lubricating oil tank and oil systemHydraulic oil, gasoline, water, silicone oilDiesterLubricating oilFluid mediumRubber parts used in, especially sealing parts.It can be said to be the most widely used and the lowest costRubber seals。
(Neoprene, Polychloroprene) is composed of chlorineButeneMonomer polymerization.VulcanizedRubber elasticityGood wear resistance, not afraid of direct sunlight, especially good weather resistance, not afraid of intense distortion, not afraid ofcryogen, resistant to dilute acid and silicone ester lubricating oil, but not resistant tophosphateIt is hydraulic oil.It is easy to crystallize and harden at low temperature, has poor storage stability, and is found in mineral oil with low aniline pointExpansion capacityLarge, the general use temperature range is - 50~150 ℃.Advantages: good elasticity and goodcompression deformationThe formula does not contain sulfur, so it is very easy to make. It has the characteristics of anti animal and vegetable oil, and will not affect the physical properties due to neutral chemicals, fat, grease, various oil products, and solvents. It has the characteristics of flame resistance.
Disadvantages: Not recommendedstrong acidSeals resistant to R12 refrigerant in nitrohydrocarbon, ester, chloroform and ketone chemicals, rubber parts or seals on household appliances.Suitable for making variousdirect contact Atmospheric, sunlight, ozone parts.Applicable to all kinds of flame resistanceChemical corrosionRubber products.
synthetic rubberComposition: synthetic rubber is made from oil and natural gasolefinAnd olefins as monomers.
The polymer of rubber has broken through the process of monomer polymerization, and the world's leading rubber factories have begun to use the rubber with higher strength, which is gathered by ultrahigh polymers, and the cost is quite low.
Rubber processing
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This process includesPlasticizing、Mixing, calendering or extrusion, molding and vulcanization, etcBasic processEach process has different requirements for products, and several auxiliary operations are provided.In order to add various required ingredients to the rubber,Raw rubberFirst, it needs to be refined to improve its plasticity;Then mixcarbon blackAnd variousRubber additiveEvenly mixed with rubber to form rubber compound;The rubber material is pressed into a blank with a certain shape;And then connect it with the calendered adhesiveTextile materials(or withMetallic materials）They are combined to form semi-finished products;Finally, after vulcanization, the plastic semi-finished products are madeHigh elasticityOfFinal product。
For products with high precision requirements,oil seal, O-ring, seal and other rubber products, which also need trimming and removingBurrFor processing, the available methods include manual trimming, mechanical trimming andFreezing trimming。
Manual trimming:labour intensityLarge, low efficiency and low qualification rate.
Mechanical trimming: mainly including punching, grinding andRound knifeTrimming is applicable to specific products with low precision requirements.
Freezing trimming: specialFreezing trimming machineThe principle of the equipment is to use liquid nitrogen（LN2) Make the rough edge of the finished product brittle at low temperature. Use specific frozen particles (bullets) to hit the rough edge to quickly remove the rough edge.Freezing trimming has become the mainstream with high efficiency, low cost and wide applicationProcess standard。
At the early stage of rubber development in China, the Rubber Products Committee was established to be responsible for rubber R&D, academicQuality supervisionAnd so on.
Samples can be taken from finished products, soaked in one or several selected media, weighed after a certain temperature time, and the type of materials can be inferred according to the weight change rate and hardness change rate.
For example, soak in 100 ℃ engine oil for 24 hours, NBR,Fluorogel，ECOCR quality and hardness change rate are very small, while NR, EPDM and SBR have more than doubled weight and great hardness change,Volumetric expansionObviously.
Take samples from finished products and place them inAging chamberAfter aging for one day, observe the aging phenomenon.Gradual aging and gradual warming can be achieved.For example, CR, NR and SBR willBrittle fractureNBR EPDM also has elasticity.When the temperature rises to 180 ℃, ordinary NBR will be brittle;At 230 ℃, HNBR will also be brittlesilica gelIt still has good elasticity.
Take a few samples and burn them in air.Observe the phenomenon.
Generally speaking, fluorogel, CR, and CSM are self extinguishing when they are out of fire. Even if the flame is ignited, the flame is much smaller than that of ordinary NR and EPDM.Of course, if carefully observed, the combustion state, color and smell will also provide us with a lot of information.For example, NBR/PVC adhesive blends, when there is a fire source, the fire is splashing and splashing, as if there is water, self extinguishing when away from the fire, thick smoke and sour taste.It should be noted that sometimesFlame retardantBut excludinghalogenThe glue will also self extinguish from the fire, which should be further inferred by other methods.
Generally speaking, the proportion of fluorine glue is the largest, more than 1.8, and the proportion of CR ECO is more than 1.3. It can be considered that these glues are the ones whose proportion is obviously larger.
Take samples from finished products and usedry iceandAlcohol manufacturingA suitableLow temperature environment。Soak the sample in a low temperature environment for 2-5 minutes, and feel the hardness at the selected temperature.For example, if the temperature is below - 40 ℃, the silica gel, which is also good at high temperature and oil resistance, is relatively soft compared with the fluorogel.
Rubber aging
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Aging phenomenon
During the processing, storage and use of rubber and its products, rubber physics is caused by the combined effect of internal and external factorschemical propertyandMechanical propertiesGradually deteriorated and finally lostuse valueThis change is called rubber aging.
It is characterized by cracking, tackiness, hardening, softening, chalking, discoloration, mildew, etc.
Aging factor
A Oxygen:Oxygen reacts with rubber molecules in the rubber by free radical chain reaction, and the molecular chains break or cross link excessively, which causes the change of rubber properties.oxidationIt is one of the important reasons for rubber aging.
(B) Ozone:OzonousChemical activityIt is much higher than oxygen and more destructive. It also breaks the molecular chain, but the effect of ozone on rubber varies with rubber deformation.As rubber for deformation (mainlyUnsaturated rubber）When, appears andStress actionCracks with straight direction, namely“Ozone cracking”；When acting on deformed rubber, only the surface is generatedOxide filmInstead of cracking.
(D) Light:The shorter the light wave, the greater the energy.It is the high-energy ones that destroy the rubberultraviolet rays。In addition to directly causing the fracture and cross-linking of rubber molecular chains, ultraviolet light is generated by rubber due to absorption of light energyFree radical, initiate and accelerate the oxidation chainReaction process。The external light plays the role of heating.Another feature of light action (different from heat action) is that it mainly grows on the surface of rubber.The specimen with high glue content will have network cracks on both sides, which is called "light outer crack".
（E）Mechanical stress: Under mechanical stressRepeated actionIt will break the rubber molecular chain and generate free radicals, which will lead to oxidationchain reaction, forming forcechemical process 。Mechanical breaking of molecular chains andMechanical activationOxidation process.Which one has the advantage depends on the conditions.In addition, it is easy to cause ozone cracking under stress.
(F) Moisture:The role of water is twofold: rubber is easy to be damaged when it is exposed to wet air or soaked in water, which is due to theWater solubilitySubstance andHydrophilic groupSuch components are dissolved, hydrolyzed or absorbed by water extraction.Especially under the alternate action of water immersion and atmospheric exposure, it will accelerate the destruction of rubber.However, in some cases, moisture does not damage rubber, and even has the effect of delaying aging.
(G) Oil:In case of long-term contact with oil medium during use, oil can penetrate into the rubber to produceswelling, resulting in the strength of rubber and othermechanical property Lower.The reason why oil can cause rubber to swell is that after oil penetrates into rubber, molecules are producedInterdiffusion, makeVulcanizateOfReticular structureChange occurs.
(H) Others:Chemical media, variable metal ionsHigh-energy radiation, electricity and biology, etc.
Adhesive repair
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The greater the polarity of rubber, the better the bonding effect.amongButyronitrileNeoprene is highly polar,Bonding strengthLarge;Natural rubber, silicone rubber and isobutylene rubber have small polarity and weak adhesion.In addition, the rubber surface often hasMold release agentOr other free additives, which hinder the bonding effect.
Use adhesiveGluingRubber, the specific methods are divided into thermal adhesion method andCold adhesion method。
The hot bonding method is to use the unvulcanized raw rubber and the glued rubber products to realize the bonding after vulcanization. The method is complex and requires heatingPressurizing equipment, inconvenient to use.
The cold bonding method is to apply the prepared adhesive on the surface of the bonded product, and then place it in the air for lamination and then cure it at room temperature.Of course, proper heating is conducive to shorteningCuring timeAnd improve bonding strength.The cold bonding method is simple and easy to operate, and it saves energy. It is a good method worth popularizing.
Different types of rubber products use different adhesives. Pay attention to the selection and do not use them at will.
Natural rubber is the liquid rubber from the rubber tree, which is processed into elastic solid and unsaturatedNatural polymer compounds。For natural rubbermethanol、toluene、IsopropanolDegrease withrasp, roughening with emery cloth.For high-strength bondingchemical treatment, ready to useconcentrated sulfuric acidSoak the glued surface 2-10min。Before bonding, bend and fold for several times to make many tiny cracks appear on the surface, which is conducive to bonding.Adhesive used: BD801 rubberAdhesiveBD817 elastic adhesive, BD818 high strength elastic adhesive, etc.
Neoprene rubber products are degreased with toluene, methanol, isopropanol, etc., and used with emery cloth, wood fileWire brushTo roughen, if chemical treatment is required, it can be soaked in concentrated sulfuric acid at room temperature for 3-30rain, washed and dried.Adhesives used: BD817 elastic adhesive, BD818 high-strength elastic adhesive, BD819 high-temperature elastic adhesive, BD801 rubber adhesive, BD802High strength rubberAdhesive, BD803 high-temperature rubber adhesive.
Nitrile rubber has good comprehensive physicsMechanical propertiesIt can be used to manufacture oil and heat resistant adhesive tape, hose, rubber plate and other products.Nitrile rubber products are degreased with methanol, roughened with wood file, emery cloth or wire brush, and can be chemically treated.
Foam rubberCommonly known as sponge, it has the functions of heat preservation, vibration prevention, sound insulation and insulation, and is used for makingDoor and window sealing stripAnti vibrationGasketEtc.During bonding, no special treatment is necessary, as long as dust and dirt are removed.Adhesives used: BD817 flexible adhesive, BD818 high strength flexible adhesive.
Rubber to metal bonding is the most effective way to connect metal to rubber.Metal can play the role of reinforcement and skeleton to rubber;Rubber enables metal to have the functions of wear resistance, vibration reduction, impact resistance, corrosion prevention, insulation, sealing, etc. The result is a combination of rigid and flexible, strong and tough.
The cold bonding of natural rubber and metal requires degreasing, roughening, degreasing and even chemical treatment.
Nitrile rubber andMetal glueTo connect, degrease first;The metal is polished with emery cloth;Rubber is roughened with grinding wheel.
(2) Bonding of rubber and glass
The rubber shall be degreased with methanol and isopropanol, roughened with wood file and grinding wheel, and used for glassacetoneAfter wiping, applymass fraction 1% KJ-550Ethanol solution, dry.
Industry relations
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Transportation
With the development of rubber industryautomotive industry Developed.In the 1960s, the automobile industry andPetrochemical industryHigh speed development makes rubberindustrial production The level has been greatly improved;In the 1970s, in order to adapt to the high-speed, safe andenergy conservation, eliminate pollution, preventPublic nuisanceThe need of such aspects has promoted the continuous emergence of new tire varieties.Raw rubber consumptionTransportationAspect accounts for a considerable proportion.For example, a Jiefang brand 4 ton truck needs more than 200 kg of rubber productsHard seatThe carriage needs to be equipped with rubber productsTotal weightMore than 300 kg, a 10000 ton ship needs nearly 10 tons of rubber productsJet airlinerNearly 600 kg of rubber is required.In sea, land and air transportation, none of them can be separated from rubber products.AsMeans of transportTyres are a major accessory.In addition to the production of ordinary tires, vigorously developRadial tire、Tubeless tireSubwaySome also use rubber tires.railway vehicle And automobile promotion and applicationRubber springShock absorbing products, air tight rubber.Large stores, stations and subways are also carrying peopleTransport belt。In addition, there are also rubber made "hovercraft"“air cushion car”Etc.
Industrial mine
industrial sector There are more large and small rubber products needed, with many varieties and wide applications, and some have special requirements.The main products are tape, hose, sealing washerRubber roller, rubber plateRubber liningandLabor protection articles。The application of tape to transport finished products in mining, coal, metallurgy and other industries is constantly emerging everywhere. For the needs of large-scale production, steel wire rope core conveyor belts andSynthetic fibreTransport belt.mineMillRubber lining, replaced by forging rubbermanganese steelThe service life has been increased by two to four times, and the noise has also been reduced. This product has been promoted worldwide.
Rubber is importantStrategic materialsIt is widely used in military and national defense. For example, a tank needs more than 800 kilograms of rubber;A 30000 ton warship needs 68 tons of rubber, almost military equipmentAir Force Facilities、National defense engineeringAll have rubber footprints.There are also many kinds of ships, tents, warehouses, protective equipment and bathing clothes made of rubber.As for the rubber products with special properties such as high temperature resistance, low temperature resistance, oil resistance and high vacuum resistance required by national defense cutting-edge technology, they are even more indispensable.along withModernization of national defenseWith the development of, it is required to be able to withstand the temperature range of minus 100-400 ℃, and to resist various acids, alkalis and oxidants. Rubber with special properties is being developed and produced.
civil engineering
For modern buildings, rubber is of great use.For example, glass window sealing rubber strips, sound insulation floors, silencing spongesRubber carpet, rainproof materials and emulsion paint on walls.Since the mid-1960s, large rubber spring cushions have been installed in buildings to reduce the vibration and noise caused by the subway.Foreign countries are also trying to produce rubber cushions to reduce the damage of earthquakes to buildings. The development of such rubber products is of great significance.Inflatable rubber, soft rubber, emulsion cement and rubber for manufacturing concrete hollow membersasphaltstayarchitectural engineeringThe application of.Mixing latex into cement can improve the elasticity andAbrasion resistance。Adding 3% rubber or latex to the asphalt to pave the road surface can prevent the cracking of the road surface and improve the impact resistance.Machinery used in construction,Transportation equipment、Protective equipmentThey all have rubber accessories.
Electrical communication
Another characteristic of rubber isInsulation performanceGood, not easy to conduct electricity.All kinds of wires and cables are made of rubber.Hard rubber is also used for makingRubber hose、Glue stick, rubber plate, partition and battery shell.In addition, it is widely used as protective equipmentInsulating gloves, insulating rubber boots, etc.
medical and health work
staymedical and health workThe department has many rubber products in use, such as those in hospitalsDepartment of Anesthesiology、Urology Department、Surgery、Brain surgery, Department of Orthopaedics, Department of Five PalacesRadiology DepartmentDiagnosis, blood transfusion, catheterization, and gastrointestinal lavageGlue colorThe gloves, ice bags and sponge cushions used for surgery are mostly rubber products.AsMedical equipmentAnd the accessories of the instrument also have rubber products.Medical rubber productsThere is often a special requirement for it, such as non-toxic, bactericidal, physiological inertia, radiation resistance, etc.Rubber towelbutyl rubber Has a higherbiologically inert , chemical stability and slightpermeableAir permeability, used to process rubberCorkIt can ensure the preservation of high moisture absorption anti business and anti-cancer preparations.silicon rubberIt is more and more widely used in manufacturing medical products, such as silicone rubberArtificial organAnd human bodyOrganizational substitutesIt has made great progress. It is also used to make drug capsules and put them in proper positions in the body, so that the drugs in the capsules can be released slowly and continuously, which can improve the efficacy and safety.
commodity reserves
Rubber is not only used for health care, but also for storing fruits and vegetables.Since 1954, great progress has been made in CA technology, which has been widely used by rubber film in the storage of fruits controlled by silicone rubber.Silicone rubber pair CO2It has superior air permeability and proper air permeability ratio with O2.The ratio of the two is 6:1, that is to say:carbon dioxideDiffusion velocityIt can pass through the silicone rubber window six times faster than oxygen.thanPolyethylene plasticThe carbon dioxide and oxygen entering the film are about 200 times faster.According to differentfruitVarietalRespiratory intensityAnd quantity, etc., made into silicone rubber dumpling of various sizes embedded inplastic filmIn control, it can maintain a proper amount of CO2 in the bag, forming a good gas storage environment, thus inhibiting the respiratory intensity of fruits and vegetables, slowing down the metabolic rate, and delaying theAfterripenessIn the process, reduce water and steam to prevent decay.From storageAppleAccording to the test comparison, the natural consumption of plastic film packaging and storage for five months is less than 0.7%, and the unused natural consumption can reach 5.83%.For another example, after one month's preservation of Xihong with silicon rubber film air conditioning account, the rate of all green and good fruits reached more than 70%, and the weight loss was 3.6%. After taking out, all fruits could turn red and mature normally.Non gas adjustedTomatoesIt turns red and mature within a week, and can't be stored any more.
Culture, education and sports
Common varietiesGall bladder、table tennis batSponge rubberNoodles, swimming soccer, toy ballsfountain penPen gall, rubber, rubber trap, rubber thread, rubber stampBlanket, balloons, sponge rubber pads, etc., are widely used in cultural and educational institutions, offices, design drawings, sports equipment, etc.
articles for daily use
In our daily life, there are many rubber products serving us and worn by urban and rural residentsConsumptionA big one.Others such as raincoatshot-water bag、Elastic band、Children's Toys, sponge cushions and latex impregnated products are playing their roles in people's life.
